2 This file documents the user interface to the GNU History library.
4 Copyright (C) 1988--2020 Free Software Foundation, Inc.
5 Authored by Brian Fox and Chet Ramey.
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26 @node Using History Interactively
27 @chapter Using History Interactively
29 @c GDB bundling modification:
30 @c @ifclear BashFeatures
35 This chapter describes how to use the @sc{gnu} History Library
36 interactively, from a user's standpoint.
37 It should be considered a user's guide.
38 For information on using the @sc{gnu} History Library in other programs,
39 see the @sc{gnu} Readline Library Manual.
42 This chapter describes how to use the @sc{gnu} History Library interactively,
43 from a user's standpoint. It should be considered a user's guide. For
44 information on using the @sc{gnu} History Library in your own programs,
45 @c GDB bundling modification:
46 @pxref{Programming with GNU History, , , history, GNU History Library}.
51 * Bash History Facilities:: How Bash lets you manipulate your command
53 * Bash History Builtins:: The Bash builtin commands that manipulate
55 * History Interaction:: What it feels like using History as a user.
60 * History Interaction:: What it feels like using History as a user.
65 @node Bash History Facilities
66 @section Bash History Facilities
67 @cindex command history
70 When the @option{-o history} option to the @code{set} builtin
71 is enabled (@pxref{The Set Builtin}),
72 the shell provides access to the @dfn{command history},
73 the list of commands previously typed.
74 The value of the @env{HISTSIZE} shell variable is used as the
75 number of commands to save in a history list.
76 The text of the last @env{$HISTSIZE}
77 commands (default 500) is saved.
78 The shell stores each command in the history list prior to
79 parameter and variable expansion
80 but after history expansion is performed, subject to the
81 values of the shell variables
82 @env{HISTIGNORE} and @env{HISTCONTROL}.
84 When the shell starts up, the history is initialized from the
85 file named by the @env{HISTFILE} variable (default @file{~/.bash_history}).
86 The file named by the value of @env{HISTFILE} is truncated, if
87 necessary, to contain no more than the number of lines specified by
88 the value of the @env{HISTFILESIZE} variable.
89 When a shell with history enabled exits, the last
90 @env{$HISTSIZE} lines are copied from the history list to the file
91 named by @env{$HISTFILE}.
92 If the @code{histappend} shell option is set (@pxref{Bash Builtins}),
93 the lines are appended to the history file,
94 otherwise the history file is overwritten.
96 is unset, or if the history file is unwritable, the history is not saved.
97 After saving the history, the history file is truncated
98 to contain no more than @env{$HISTFILESIZE} lines.
99 If @env{HISTFILESIZE} is unset, or set to null, a non-numeric value, or
100 a numeric value less than zero, the history file is not truncated.
102 If the @env{HISTTIMEFORMAT} is set, the time stamp information
103 associated with each history entry is written to the history file,
104 marked with the history comment character.
105 When the history file is read, lines beginning with the history
106 comment character followed immediately by a digit are interpreted
107 as timestamps for the following history entry.
109 The builtin command @code{fc} may be used to list or edit and re-execute
110 a portion of the history list.
111 The @code{history} builtin may be used to display or modify the history
112 list and manipulate the history file.
113 When using command-line editing, search commands
114 are available in each editing mode that provide access to the
115 history list (@pxref{Commands For History}).
117 The shell allows control over which commands are saved on the history
118 list. The @env{HISTCONTROL} and @env{HISTIGNORE}
119 variables may be set to cause the shell to save only a subset of the
122 shell option, if enabled, causes the shell to attempt to save each
123 line of a multi-line command in the same history entry, adding
124 semicolons where necessary to preserve syntactic correctness.
126 shell option causes the shell to save the command with embedded newlines
127 instead of semicolons.
128 The @code{shopt} builtin is used to set these options.
129 @xref{The Shopt Builtin}, for a description of @code{shopt}.
131 @node Bash History Builtins
132 @section Bash History Builtins
133 @cindex history builtins
135 Bash provides two builtin commands which manipulate the
136 history list and history file.
143 @code{fc [-e @var{ename}] [-lnr] [@var{first}] [@var{last}]}
144 @code{fc -s [@var{pat}=@var{rep}] [@var{command}]}
147 The first form selects a range of commands from @var{first} to
148 @var{last} from the history list and displays or edits and re-executes
151 @var{last} may be specified as a string (to locate the most recent
152 command beginning with that string) or as a number (an index into the
153 history list, where a negative number is used as an offset from the
154 current command number).
156 When listing, a @var{first} or @var{last} of 0 is equivalent to -1
157 and -0 is equivalent to the current command (usually the @code{fc}
159 otherwise 0 is equivalent to -1 and -0 is invalid.
161 If @var{last} is not specified, it is set to
162 @var{first}. If @var{first} is not specified, it is set to the previous
163 command for editing and @minus{}16 for listing. If the @option{-l} flag is
164 given, the commands are listed on standard output. The @option{-n} flag
165 suppresses the command numbers when listing. The @option{-r} flag
166 reverses the order of the listing. Otherwise, the editor given by
167 @var{ename} is invoked on a file containing those commands. If
168 @var{ename} is not given, the value of the following variable expansion
169 is used: @code{$@{FCEDIT:-$@{EDITOR:-vi@}@}}. This says to use the
170 value of the @env{FCEDIT} variable if set, or the value of the
171 @env{EDITOR} variable if that is set, or @code{vi} if neither is set.
172 When editing is complete, the edited commands are echoed and executed.
174 In the second form, @var{command} is re-executed after each instance
175 of @var{pat} in the selected command is replaced by @var{rep}.
176 @var{command} is interpreted the same as @var{first} above.
178 A useful alias to use with the @code{fc} command is @code{r='fc -s'}, so
179 that typing @samp{r cc} runs the last command beginning with @code{cc}
180 and typing @samp{r} re-executes the last command (@pxref{Aliases}).
187 history -d @var{offset}
188 history -d @var{start}-@var{end}
189 history [-anrw] [@var{filename}]
190 history -ps @var{arg}
193 With no options, display the history list with line numbers.
194 Lines prefixed with a @samp{*} have been modified.
195 An argument of @var{n} lists only the last @var{n} lines.
196 If the shell variable @env{HISTTIMEFORMAT} is set and not null,
197 it is used as a format string for @var{strftime} to display
198 the time stamp associated with each displayed history entry.
199 No intervening blank is printed between the formatted time stamp
200 and the history line.
202 Options, if supplied, have the following meanings:
206 Clear the history list. This may be combined
207 with the other options to replace the history list completely.
209 @item -d @var{offset}
210 Delete the history entry at position @var{offset}.
211 If @var{offset} is positive, it should be specified as it appears when
212 the history is displayed.
213 If @var{offset} is negative, it is interpreted as relative to one greater
214 than the last history position, so negative indices count back from the
215 end of the history, and an index of @samp{-1} refers to the current
216 @code{history -d} command.
218 @item -d @var{start}-@var{end}
219 Delete the history entries between positions @var{start} and @var{end},
220 inclusive. Positive and negative values for @var{start} and @var{end}
221 are interpreted as described above.
224 Append the new history lines to the history file.
225 These are history lines entered since the beginning of the current
226 Bash session, but not already appended to the history file.
229 Append the history lines not already read from the history file
230 to the current history list. These are lines appended to the history
231 file since the beginning of the current Bash session.
234 Read the history file and append its contents to
238 Write out the current history list to the history file.
241 Perform history substitution on the @var{arg}s and display the result
242 on the standard output, without storing the results in the history list.
245 The @var{arg}s are added to the end of
246 the history list as a single entry.
250 When any of the @option{-w}, @option{-r}, @option{-a}, or @option{-n} options is
251 used, if @var{filename}
252 is given, then it is used as the history file. If not, then
253 the value of the @env{HISTFILE} variable is used.
258 @node History Interaction
259 @section History Expansion
260 @cindex history expansion
262 The History library provides a history expansion feature that is similar
263 to the history expansion provided by @code{csh}. This section
264 describes the syntax used to manipulate the history information.
266 History expansions introduce words from the history list into
267 the input stream, making it easy to repeat commands, insert the
268 arguments to a previous command into the current input line, or
269 fix errors in previous commands quickly.
272 History expansion is performed immediately after a complete line
273 is read, before the shell breaks it into words, and is performed
274 on each line individually. Bash attempts to inform the history
275 expansion functions about quoting still in effect from previous lines.
278 History expansion takes place in two parts. The first is to determine
279 which line from the history list should be used during substitution.
280 The second is to select portions of that line for inclusion into the
281 current one. The line selected from the history is called the
282 @dfn{event}, and the portions of that line that are acted upon are
283 called @dfn{words}. Various @dfn{modifiers} are available to manipulate
284 the selected words. The line is broken into words in the same fashion
285 that Bash does, so that several words
286 surrounded by quotes are considered one word.
287 History expansions are introduced by the appearance of the
288 history expansion character, which is @samp{!} by default.
290 History expansion implements shell-like quoting conventions:
291 a backslash can be used to remove the special handling for the next character;
292 single quotes enclose verbatim sequences of characters, and can be used to
293 inhibit history expansion;
294 and characters enclosed within double quotes may be subject to history
295 expansion, since backslash can escape the history expansion character,
296 but single quotes may not, since they are not treated specially within
300 When using the shell, only @samp{\} and @samp{'} may be used to escape the
301 history expansion character, but the history expansion character is
302 also treated as quoted if it immediately precedes the closing double quote
303 in a double-quoted string.
307 Several shell options settable with the @code{shopt}
308 builtin (@pxref{The Shopt Builtin}) may be used to tailor
309 the behavior of history expansion. If the
310 @code{histverify} shell option is enabled, and Readline
311 is being used, history substitutions are not immediately passed to
313 Instead, the expanded line is reloaded into the Readline
314 editing buffer for further modification.
315 If Readline is being used, and the @code{histreedit}
316 shell option is enabled, a failed history expansion will be
317 reloaded into the Readline editing buffer for correction.
318 The @option{-p} option to the @code{history} builtin command
319 may be used to see what a history expansion will do before using it.
320 The @option{-s} option to the @code{history} builtin may be used to
321 add commands to the end of the history list without actually executing
322 them, so that they are available for subsequent recall.
323 This is most useful in conjunction with Readline.
325 The shell allows control of the various characters used by the
326 history expansion mechanism with the @code{histchars} variable,
327 as explained above (@pxref{Bash Variables}). The shell uses
328 the history comment character to mark history timestamps when
329 writing the history file.
333 * Event Designators:: How to specify which history line to use.
334 * Word Designators:: Specifying which words are of interest.
335 * Modifiers:: Modifying the results of substitution.
338 @node Event Designators
339 @subsection Event Designators
340 @cindex event designators
342 An event designator is a reference to a command line entry in the
344 Unless the reference is absolute, events are relative to the current
345 position in the history list.
346 @cindex history events
352 Start a history substitution, except when followed by a space, tab,
353 the end of the line, @samp{=} or @samp{(} (when the
354 @code{extglob} shell option is enabled using the @code{shopt} builtin).
356 @ifclear BashFeatures
357 Start a history substitution, except when followed by a space, tab,
358 the end of the line, or @samp{=}.
361 @item @code{!@var{n}}
362 Refer to command line @var{n}.
364 @item @code{!-@var{n}}
365 Refer to the command @var{n} lines back.
368 Refer to the previous command. This is a synonym for @samp{!-1}.
370 @item @code{!@var{string}}
371 Refer to the most recent command
372 preceding the current position in the history list
373 starting with @var{string}.
375 @item @code{!?@var{string}[?]}
376 Refer to the most recent command
377 preceding the current position in the history list
378 containing @var{string}.
380 @samp{?} may be omitted if the @var{string} is followed immediately by
382 If @var{string} is missing, the string from the most recent search is used;
383 it is an error if there is no previous search string.
385 @item @code{^@var{string1}^@var{string2}^}
386 Quick Substitution. Repeat the last command, replacing @var{string1}
387 with @var{string2}. Equivalent to
388 @code{!!:s^@var{string1}^@var{string2}^}.
391 The entire command line typed so far.
395 @node Word Designators
396 @subsection Word Designators
398 Word designators are used to select desired words from the event.
399 A @samp{:} separates the event specification from the word designator. It
400 may be omitted if the word designator begins with a @samp{^}, @samp{$},
401 @samp{*}, @samp{-}, or @samp{%}. Words are numbered from the beginning
402 of the line, with the first word being denoted by 0 (zero). Words are
403 inserted into the current line separated by single spaces.
410 designates the preceding command. When you type this, the preceding
411 command is repeated in toto.
414 designates the last argument of the preceding command. This may be
415 shortened to @code{!$}.
418 designates the second argument of the most recent command starting with
419 the letters @code{fi}.
423 Here are the word designators:
428 The @code{0}th word. For many applications, this is the command word.
434 The first argument; that is, word 1.
440 The first word matched by the most recent @samp{?@var{string}?} search,
441 if the search string begins with a character that is part of a word.
443 @item @var{x}-@var{y}
444 A range of words; @samp{-@var{y}} abbreviates @samp{0-@var{y}}.
447 All of the words, except the @code{0}th. This is a synonym for @samp{1-$}.
448 It is not an error to use @samp{*} if there is just one word in the event;
449 the empty string is returned in that case.
452 Abbreviates @samp{@var{x}-$}
455 Abbreviates @samp{@var{x}-$} like @samp{@var{x}*}, but omits the last word.
456 If @samp{x} is missing, it defaults to 0.
460 If a word designator is supplied without an event specification, the
461 previous command is used as the event.
464 @subsection Modifiers
466 After the optional word designator, you can add a sequence of one or more
467 of the following modifiers, each preceded by a @samp{:}.
468 These modify, or edit, the word or words selected from the history event.
473 Remove a trailing pathname component, leaving only the head.
476 Remove all leading pathname components, leaving the tail.
479 Remove a trailing suffix of the form @samp{.@var{suffix}}, leaving
483 Remove all but the trailing suffix.
486 Print the new command but do not execute it.
490 Quote the substituted words, escaping further substitutions.
493 Quote the substituted words as with @samp{q},
494 but break into words at spaces, tabs, and newlines.
495 The @samp{q} and @samp{x} modifiers are mutually exclusive; the last one
499 @item s/@var{old}/@var{new}/
500 Substitute @var{new} for the first occurrence of @var{old} in the
502 Any character may be used as the delimiter in place of @samp{/}.
503 The delimiter may be quoted in @var{old} and @var{new}
504 with a single backslash. If @samp{&} appears in @var{new},
505 it is replaced by @var{old}. A single backslash will quote
507 If @var{old} is null, it is set to the last @var{old}
508 substituted, or, if no previous history substitutions took place,
509 the last @var{string}
510 in a !?@var{string}@code{[?]}
512 If @var{new} is is null, each matching @var{old} is deleted.
513 The final delimiter is optional if it is the last
514 character on the input line.
517 Repeat the previous substitution.
521 Cause changes to be applied over the entire event line. Used in
522 conjunction with @samp{s}, as in @code{gs/@var{old}/@var{new}/},
526 Apply the following @samp{s} or @samp{&} modifier once to each word